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CHAPTER 27 1091 
 
(b) The starting materials are a diol and a diisocyanate, 
which can be linked together as carbamate groups, 
giving the following polyurethane: 
 
 
 
(c) The starting materials are a diol and phosgene, which 
will react with each other to give carbonate groups, and 
thus the following polycarbonate: 
 
 
 
27.30. 
(a) The starting materials are a diacid and a diamine, 
which can be linked together via amide groups, giving 
the following polymer: 
 
 
 
(b) Quiana is a polyamide. 
(c) Quiana is a step-growth polymer, because each of the 
growing oligomers has two growth points. 
(d) Quiana is a condensation polymer because it is made 
via a condensation process (between carboxylic acid and 
amino groups). 
 
27.31. 
(a) Each of the amide groups can be made from the 
reaction between a carboxylic acid and an amino group. 
Therefore, this polymer can be made from the following 
monomer, which bears both the amino group and the 
carboxylic acid group: 
 
 
 
(b) Each of the ester groups can be made from the 
reaction between a carboxylic acid and an alcohol. 
Therefore, this polymer can be made from the following 
monomer, which bears both a hydroxyl group and a 
carboxylic acid group: 
 
 
27.32. The starting materials are a diol and phosgene, 
which will react with each other to give carbonate 
groups, and thus the following polycarbonate: 
 
 
 
27.33. 
(a) Each monomer has two growth points, so we expect 
that polymerization will generate a step-growth polymer.
 
(b) When these monomers react are used to form a 
copolymer, the growing polymer chain has only one 
growth point, so we expect that polymerization will 
generate a chain-growth polymer. 
 
27.34. Nitro groups are among the most powerful 
electron-withdrawing groups, and a nitro group stabilizes 
a negative charge on an adjacent carbon atom, thereby 
facilitating anionic polymerization. 
 
27.35. Shower curtains are made from PVC, which is a 
thermoplastic polymer. To prevent the polymer from 
being brittle, the polymer is prepared in the presence of 
plasticizers which become trapped between the polymer 
chains where they function as lubricants. Over time, the 
plasticizers evaporate, and the polymer becomes brittle. 
 
27.36. 
(a) Polyformaldehyde is a polymer that is assembled 
from repeating formaldehyde (CH2O) units, as shown: 
 
 
 
(b) Polyformaldehyde has repeating ether groups, so it is 
a polyether. 
(c) The growing polymer chain has only one growth 
point, so polyformaldehyde is classified as a chain-
growth polymer. 
(d) Polyformaldehyde is an addition polymer, because it 
is formed via successive addition reactions (involving 
the bond in each molecule of formaldehyde). 
 
27.37. It bears an electron-withdrawing group (CN) that 
can stabilize a negative charge via resonance, but it also 
bears an electron-donating group (OMe) that can 
stabilize a positive charge via resonance. 
 
27.38. The nitro group serves as a reservoir of electron 
density that stabilizes a negative charge via resonance 
(see Chapter 18). 
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